The hydraulic conductivity of peat with respect to scaling, botanical composition, and greenhouse gas transport: Mini-aquifer tests from the Red Lake Peatland, Minnesota

Paul H. Glaser, Joshua Rhoades, Andrew S. Reeve

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5 Scopus citations

Abstract

Hydraulic conductivity (K) is a key but problematic parameter in groundwater models particularly those that simulate flow in weak, readily deformable media, such as peat deposits. As a result, K represents a critical source of error in models that couple hydrological processes with the carbon balance of peatlands, a globally important source for greenhouse gases. We therefore conducted mini-aquifer tests on two mesoscale bog landforms within the large 1300 km2 Red Lake Peatland of northern Minnesota. These tests offer the dual advantage of determining the fine-scale distribution of K within a large (>900 m3) model domain. In addition, the stress created by a 24 h pumping operation should be capable of mobilizing pools of biogenic gases thoughout a deep peat deposit. The pumping results were monitored by 24 to 38 wells in order to calibrate a 3D finite-volume groundwater model with the aid of PEST (Parameter Estimation Analysis). High K values were determined at a Bog Forest (10−5 to 10−6 m s−1) and Bog Lawn (10−3 to 10−4 m s−1) sites, throughout their deep (>4 m) peat profiles. These tests also detected vertically continuous zones of unexpectedly high or low K values in contrast to the horizontal bedding planes and increasing degree of decomposition with depth. The vertical K zones are suggestive of three different modes of bubble transport that either locally dilate or partially block the peat pores. In addition, the tests provided new insights on a conceptual model linking K to the development of all large (>20 km2) forested bog complexes in mid-continental boreal North America.

Original languageEnglish (US)
Article number125686
JournalJournal of Hydrology
Volume596
DOIs
StatePublished - May 1 2021

Bibliographical note

Funding Information:
This research was funded by the National Science Foundation (award EAR-0628349). Reeve and Rhoades also received support from the Maine Agricultural and Forestry Experiment Station (ME0H60049412). We thank D.I. Siegel, D.O. Rosenberry, D.R. Janecky, Nigel Roulet, and X. Comas for critically reading the manuscripts and offering many valuable suggestions. We also thank Lee Andrew, W. Cowen, and C. Flynn of Brainerd Helicopter Service for helicopter access to the field site and the Minnesota Department of Natural Resources for providing a base station for field work.

Funding Information:
This research was funded by the National Science Foundation (award EAR-0628349 ). Reeve and Rhoades also received support from the Maine Agricultural and Forestry Experiment Station ( ME0H60049412 ). We thank D.I. Siegel, D.O. Rosenberry, D.R. Janecky, Nigel Roulet, and X. Comas for critically reading the manuscripts and offering many valuable suggestions. We also thank Lee Andrew, W. Cowen, and C. Flynn of Brainerd Helicopter Service for helicopter access to the field site and the Minnesota Department of Natural Resources for providing a base station for field work.

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

  • Biogenic gas bubbles
  • Hydraulic conductivity
  • Mini-aquifer test
  • PEST (Parameter Estimation Analysis)
  • Peatlands

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